1. Field of the Invention
This invention relates to an image storage apparatus, an image storage method, and a storage medium for capturing and storing image data taken by a digital camera and the like.
2. Description of Related Art
In recent years, digital cameras have been produced as consumer appliances due to the technical progress of semiconductors, and ordinary people have been using them. The digital cameras are different from ordinary cameras in that the digital cameras can take a great number of pictures, a user can immediately regenerate and confirm the pictures, and the user can erase the failed picture and take a picture again. This enables the user to take pictures without worrying about failures.
In the conventional digital cameras, a flash memory in the digital camera is used for recording the captured data. When a memory capacity of the flash memory is full, the user downloads the data of the flash memory into a general purpose computer or special equipment by using a communication means such as RS232C and IrDA and then erases the data from the flash memory. Then, the user takes a picture again.
Recently, however, a removable medium as an electronic film, which can be used in the same manner as film of a silver halide camera, has been used as a memory for recording data captured by the digital cameras. When the removable medium is full, it can be replaced by a new removable medium. This enables the user to take pictures without worrying about the capacity of the medium.
The removable medium as the electronic film includes a PC card (PCMCIA) adopted from a notebook computer. Due to the reduction in the size of the digital camera, a CF (Compact Flash) card smaller than the PC card has been increasingly used as the removable medium.
The mainstream size of an image taken by the digital camera was a VGA size (640 pixels×480 pixels) taken by a CCD of a 350,000 pixel class in the early stages. Now, the mainstream image size is an XGA size (1024 pixels×768 pixels) of an 800,000 pixels class and an SXGA (1280 pixels×1024 pixels) of a 1,300,000 class. The image size of some digital cameras is of higher quality close to the image size of a silver halide camera. Accordingly, the electronic film is required to have a larger capacity.
Most of the taken images are now handled by a system using a general purpose computer (PC) as shown in FIG. 1. FIG. 1 shows a conventional system using the general purpose PC.
In FIG. 1, reference numeral 100 denotes the general purpose computer (e.g., a PC for Windows 95); 101, a PC card reader; 102, an SCSI used as an interface standard for connecting to PC peripheral equipment; 103, a CF card used as electronic film for the digital camera; and 104, a CF adapter for converting the CF card 103 into a PC card.
A description will now be given of the procedure for downloading data in this system. First, a power supply for the general purpose PC 100 and the PC card reader is turned on to activate the system. Then, an application for managing images is activated.
Then, the CF card adapter 104 is attached to the CF card 103, which contains image data taken by the digital camera. Consequently, the CF card 103 is converted into an interface of the PC card, and is used as a normal PC card. The PC card is inserted into a slot of a PC card interface of the PC card reader 101.
From an application (for example an image management software currently on the market) operating on the general purpose PC 100, the CF card 103 inserted into the PC card reader 101 is seen as an SCSI drive. Necessary image data are captured from the CF card 103 seen as the SCSI drive by means of the application. At the same time, the application produces thumbnail images for every image in order to manage the images. The selected images are processed using a list of the thumbnail images; for example, the edition (e.g., 90°—rotation and trimming) and the slide show of the images.
The above sequence of operation requires the steps of activating the computer and the application software. This requires a lot of time for downloading the images recorded in the CF card.
To address this problem, there has been developed an image storage apparatus that replaces the PC, which takes a lot of time to activate. The image storage apparatus preferably has a function of easily storing the images of the electronic film, and a function of erasing the images from the electronic film and reusing the electronic film, and is preferably capable of executing these functions quickly. Moreover, the image storage apparatus preferably has a function of enabling a family to look at images on a TV in a living room and the like. In addition, the cost of the image storage apparatus needs to be lowered as much as possible.
Such an image storage apparatus handles original images and corresponding thumbnail images, and manages the original images by means of the thumbnail images. For example, if a plurality of original images are stored, as many thumbnail images are stored in correlation with the respective original images and are displayed as indices for indicating the original images. A desired thumbnail image is selected from the thumbnail images displayed as indices in order to designate the original image to be processed. The designated original image is read and displayed in a large size on a TV, or is edited.
In the digital camera, an LCD (a liquid crystal display) is attached to a body of the camera, or a function of outputting the taken images to a TV is provided at the body of the camera. Thumbnail images corresponding to the taken original images are generated and used for managing the original images.
Ordinarily, the size of the thumbnail image differs (e.g., 80 pixels×60 pixels and 96 pixels×64 pixels) according to the types and manufacturers of the digital cameras. In many cases, the size of thumbnail images generated by the digital camera is different from the size of thumbnail images handled by the image storage apparatus.
To address this problem, the image storage apparatus is provided with a means for generating thumbnail images from original image data captured from the electronic film. Japanese Patent Provisional Publication No. 8-63486 discloses what kinds of directories are used to manage the images.
The conventional image storage apparatus, however, must generate the thumbnail images for managing the images. To generate the thumbnail images, the JPEG-encoded original image data must be JPEG-decoded and resized to the size of thumbnail images. Therefore, it takes much time to generate the thumbnail images, and it is difficult to complete the whole process within a short time even in the case where the image data in the electronic film are downloaded from the electronic film, which are then used as new electronic film in the digital camera.